Cutter knife for left handed and right handed persons

ABSTRACT

A cutter knife of which a blade connected to a slider is slidably held in an elongated sleeve member. The slider is provided with a first engagement protrusion and a second engagement protrusion located on a forward end and a backward end in sliding direction of the slider, one of which is to be inserted into a connection hole of the blade for connecting the slider and the blade. A distance from each of the first and the second engagement protrusions to the inner surface of the sleeve member when the slider is inserted into the sleeve member is set smaller than a distance between the connection hole and a back of the blade, and thereby the blade back is biased against the inner surface of the sleeve member for protecting the blade edge. When inserting direction of the slider is reversed, biased direction of the blade is also reversed.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a cutter knife of which blade isslidably retracted into an elongated sleeve member. In particular, thepresent invention relates to a cutter knife, wherein a space is keptbetween a blade edge and an inner wall of the sleeve member, in order toprevent that the blade edge is destroyed from rubbing against the innerwall of the sleeve member, while sliding.

[0003] 2. Description of the Related Art

[0004] FIGS. 1 to 3B show a cutter knife, which is disclosed in Japaneseexamined utility model publication No. 59-20872. A blade 1 and a slider10 are connected in an elongated sleeve member 20. A user can manipulatethe slider 10 to cause the blade 1 to slide, so that the blade 1 isprotruded from and retracted into the sleeve member 20. The sleevemember 20 is provided with a pair of side walls 20 a and 20 b, whichextend in parallel with sliding direction of the blade 1. Being guidedbetween the side walls 20 a and 20 b, the blade 1 and the slider 10slide in the longitudinal direction of the cutter knife.

[0005] As shown in FIG. 2, a spring member 11 is provided on one side ofthe slider 10. Under the biasing force by the spring member 11, theblade back 1 b is pressed onto the inner surface of the side wall 20 a(the side wall at upper location in FIG. 1). As a result, a space iskept between the blade edge la and the inner surface of the side wall 20b(the side wall at lower location in FIG. 1). Thanks to such the space,the blade edge 1 a can be prevented from rubbing against the innersurface of the side wall 20 b, and thus the blade edge 1 a can beprotected from destroy.

[0006] The slider 10 is provided with two engagement protrusions 15, 16,which are located at forward end and at backward end of the slidingdirection of the slider 10. One of the engagement protrusions isinserted into a connection hole 2 of the blade 1, so that the slider 10and the blade 1 are connected. As shown inside the dash-lined frame inFIG. 1, when the inserting direction of the slider 10 into the sleevemember 20 is reversed, the engagement protrusion 16 is now engaged withthe connection hole 2, rather than the engagement protrusion 15. As aresult, the direction of the biasing force applied to the blade 1 by thespring member 11 is also reversed. In other words; when the insertingdirection of the slider 10 is reversed, and further the blade 1 isturned so that the edge 1 a faces upward in FIG. 1, the blade back 1 bis pressed onto the inner surface of the side wall 20 bunder the biasingforce by the spring member 11. As a result, a space is kept between theblade edge 1 a and the inner surface of the side wall 20 a.

[0007] The reason why the biasing direction of the blade is reversed isfor accommodating the cutter knife to both of the right handed users andthe left handed users. This is explained with reference to FIGS. 3A and3B, which are partially broken end elevations seen from the user sidewho is grasping the cutter knife.

[0008]FIG. 3A shows a situation that the left handed user uses thecutter knife, which corresponds to the case the slider 10 shown insidethe dash-lined frame in FIG. 1 and the blade 1 connected thereto areinserted into the sleeve member 20. In FIG. 3A, the blade edge 1 a facesdownwards. The user grasps the cutter knife in left hand, andmanipulates with left thumb finger the slider knob 18 attached to theslider 10 for protruding and retracting the blade 1. The blade 1 isconnected with the slider 10 at the engagement protrusion 16, and theengagement protrusion 15 in disengagement can be seen from the userside. The slider knob 18 is in thread engagement with a treaded hole 17provided on the slider.

[0009]FIG. 3B shows a situation that the right handed user uses thecutter knife, which corresponds to the case the slider 10 and the blade1 connected thereto are inserted into the sleeve member 20 as shown bythe solid-lined arrow in FIG. 1. Also in FIG. 3B, the blade edge 1 afaces downwards. The user grasps the cutter knife in right hand, andmanipulates with right thumb finger the slider knob 18 attached to theslider 10 for protruding and retracting the blade 1. The blade 1 isconnected with the slider 10 at the engagement protrusion 15, and theengagement protrusion 16 in disengagement can be seen from the userside.

[0010] In the conventional cutter knife as explained above, withreversing the inserting direction of the slider, the right handed usersand the left handed users can properly use it. However, the constructionof the slider is inconveniently complicated. Specifically, in order toprovide the spring member 11 constructed as shown in FIG. 2 on theslider 10, it is necessary to attach a separate member of leaf spring onthe slider 10. Alternatively, even if a spring portion is integrallyformed into the slider 10, a very complicated mold would be necessary,which would cause the cost increasing.

SUMMERY OF THE INVENTION

[0011] In view of the above-mentioned circumstance, an object of thepresent invention is to provide a cutter knife, which has more simpleconstruction and can be properly used by both of the right handed usersand the left handed users.

[0012] According to the present invention, there is provided a cutterknife, comprising: an elongated sleeve member, a blade slidably held inthe sleeve member, and a slider which is connected with the blade and isslidable in the sleeve member in longitudinal direction, via which theblade is manipulated to protrude from and retracted into the sleevemember, wherein the slider is provided with a first engagementprotrusion and a second engagement protrusion located on a forward endand a backward end in sliding direction of the slider, one of which isto be inserted into a connection hole of the blade for connecting theslider and the blade, a distance from each of the first engagementprotrusion and the second engagement protrusion to an inner surface ofthe sleeve member when the slider is inserted into the sleeve member isset smaller than a distance between the connection hole and a back ofthe blade, and thereby the back of the blade is biased against the innersurface of the sleeve member, so that a space is kept between an edge ofthe blade and an opposite another inner surface of the sleeve memberwhile the blade is sliding, and the first engagement protrusion and thesecond engagement protrusion are located in straight and parallel withthe sliding direction of the slider, thereby when inserting direction ofthe slider into the sleeve member is reversed, biased direction of theblade is also reversed.

[0013] In the cutter knife constructed as above, when facing directionof the blade and inserting direction of the slider are reversed, thebiased direction of the blade against the inner surface of the sleevemember is reversed. Such the advantage itself can be achieved also inthe above-mentioned conventional cutter knife. However, in the presentinvention, the biasing force is attributed to the location (orarrangement) of the engagement protrusions provided on the slider. Thus,any separate members (such as a spring member 11) for providing thebiasing force are not necessary, and thanks to this, the construction ofthe slider can be more simplified than in the conventional cutter knife.Accordingly, the cutter knife can be easily manufactured, leading to thelower manufacturing cost and the lower selling price.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] This and other objects and features of the present invention willbecome apparent from the following description taken in conjunction withthe preferred embodiments thereof with reference to the accompanyingdrawings.

[0015]FIG. 1 is an explanatory view showing a conventional cutter knife.

[0016]FIG. 2 is a perspective view of a slider which is employed in thecutter knife in FIG. 1.

[0017]FIG. 3A is an explanatory view showing a condition that the cutterknife in FIG. 1 is used by a left handed user.

[0018]FIG. 3B is an explanatory view showing a condition that the cutterknife in FIG. 1 is used by a right handed user.

[0019]FIG. 4 is an exploded perspective view of a cutter knife accordingto an embodiment of the present invention.

[0020]FIG. 5 is a plan view of a slider which is employed in the cutterknife in FIG. 4.

[0021]FIGS. 6A and 6B are respectively an explanatory view explainingrelationship between engagement protrusions and biasing direction.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0022] With reference to FIGS. 4 to 6B, a description is made below on acutter knife, according to an embodiment of the present invention. FIG.4 shows an exploded perspective view of the cutter knife.

[0023] A slider 50 is slidably inserted into a sleeve member 20, and isprovided with a first engagement protrusion 54 and a second engagementprotrusion 58, which are located on a forward end and a backward end insliding direction of the slider. In FIG. 4, the first engagementprotrusion 54 is to be inserted into a connection hole 2 of the blade 1.When the inserting direction of the slider 50 is reversed, the secondengagement protrusion 58 is to be inserted into a connection hole 2 ofthe blade 1. Note that, in such the case, the blade 50 is turnedreversed so that an edge 1 a of the blade 50 faces oppositely.

[0024] A separate member 51, which is to be attached to the slider, isemployed as a grip face of the slider 50. However, alternatively aslider integrally including a grip face would be molded. In practice, auser fits his finger on the grip face to manipulate the blade 50.

[0025] Note that in the drawings a lock mechanism for blade position isomitted, because the present invention is directed to a mechanism forbiasing a blade. However, in an actual product, some lock mechanism maybe provided for locking the blade in a position in practical use. As alock mechanism, it can be a screw-type knob 18 as shown in FIGS. 1 to 3.Further, the lock mechanism can be what utilizes an elastic engagementbetween a spring member on the slider and recesses on the body of thecutter knife (not shown). Note that, the advantage of the simplicity ofthe slider construction brought by the present invention is directedonly to a mechanism, by which the blade back is biased against the innersurface of the sleeve member.

[0026]FIG. 5 is a plan view of the slider 50, which explains theconstruction of the slider 50. In order to realize a smooth sliding ofthe slider 50 in the sleeve member 20, the maximum width “W” of theslider 50 is sized nearly equal to the distance between the opposingside walls 20 a and 20 bof the sleeve member 20. The first engagementprotrusion 54 and the second engagement protrusion 58 are offset in thesame direction (upper side in FIG. 5) with respect to the center-line“L” shown in FIG. 5. The first engagement protrusion 54 and the secondengagement protrusion 58 are located in straight and parallel with thecenter-line “L” (that is, parallel with the sliding direction of theslider).

[0027] The first engagement protrusion 54 is located on a firstextending portion 52, which projects from the grip face 51 in onedirection. On the other hand, the second engagement protrusion 58 islocated on a second extending portion 56, which projects from the gripface 51, oppositely to the first extending portion 52.

[0028] A U-shaped opening 53 and a U-shaped opening 57 are formed on thefirst extending portion 52 and the second extending portion 56, so thatthe configuration of the first extending portion 52 and the secondextending portion 56 are frame-like. Thanks to such the configuration,both of the extending portions 52 and 56 can be resiliently deformed,and this deformation allows the blade to be biased against the innersurface of the sleeve member, as explained after. Note that theconfiguration of the slider is not limited to specific one in thepresent invention, as far as “the distance from each of the first andthe second engagement protrusions 54, 58 to the inner surface of theside wall when the slider 50 is inserted into the sleeve member 20” isset smaller than “the distance between the connection hole 2 and theblade back 1 a”, and thereby the blade can be resiliently biased againstthe inner surface of the sleeve member.

[0029] The advantage due to the above-mentioned arrangement of the firstand the second engagement protrusions 54, 58 is explained below, withreference to FIGS. 6A and 6B. In FIGS. 6A and 6B, the dashed linesrunning on both sides of the blade 1 and the slider 50 almost correspondto the distance between the opposing side walls 20 a and 20 bof thesleeve member 20 (refer to FIG. 4). That is, the blade 1 and the slider50 slide in the longitudinal direction, with making their center-linecorrespond to intermediary between the side walls 20 a and 20 b.

[0030] As explained above, the first and the second engagementprotrusions 54, 58 are offset from the center line “L”. Thus, in orderto insert the blade 1 and the slider 50 after assembled into the sleevemember 20, it is necessary to deform the first and the second extendingportions 52, 56 on which the first and the second engagement protrusions54, 58 are provided, so that the first and the second engagementprotrusions 54, 58 are aligned to the center line “L”. Thanks to this, abiasing force is generated, which urges the blade back 1 b onto theinner surface of the sleeve member. As a result, a space is kept betweenthe blade edge 1 a and the inner surface of the sleeve member, so thatthe blade edge 1 a can be protected.

[0031] The first engagement protrusion 54 and the second engagementprotrusion 58 are located in straight and parallel with the slidingdirection of the slider 50. Accordingly, when the inserting direction ofthe slider 50 into the sleeve member 20 is reversed, the direction ofthe biasing is also reversed. Since the blade 50 is turned around itslongitudinal axis so that the blade edge 1 a faces oppositely when theinserting direction of the slider 50 is reversed, the blade back isalways pressed onto the inner surface of the sleeve member.

[0032] In the shown embodiment, since the blade is provided with theconnection hole 2 at the center of width, the two engagement protrusions54, 58 are offset in the same direction from the center line “L”. Thatis, under such the construction, “a distance from each of the firstengagement protrusion and the second engagement protrusion to the innersurface of the side wall when the slider is inserted into the sleevemember” is made smaller than “a distance between the connection hole andthe back of the blade”.

[0033] Even in a cutter knife of which the connection hole is notlocated at the center of width, the same effect would be realized bysatisfying the relationship of the above two distances. Thus, thepresent invention can be applied to any blades, which have theconnection hole located at any position in its width direction. Thedegree of the biasing force can be adjusted by the difference betweenthe above two directions.

[0034] Although the present invention has been fully described inconnection with the preferred embodiment thereof with reference to theaccompanying drawings, it is to be noted that various changes andmodifications are apparent to those skilled in the art. Such changes andmodifications are to be understood as included within the scope of thepresent invention as defined by the appended claims unless they departtherefrom.

What is claimed is:
 1. A cutter knife, comprising: an elongated sleeve member, a blade slidably held in the sleeve member, and a slider which is connected with the blade and is slidable in the sleeve member in longitudinal direction, via which the blade is manipulated to protrude from and retracted into the sleeve member, wherein the slider is provided with a first engagement protrusion and a second engagement protrusion located on a forward end and a backward end in sliding direction of the slider, one of which is to be inserted into a connection hole of the blade for connecting the slider and the blade, a distance from each of the first engagement protrusion and the second engagement protrusion to an inner surface of the sleeve member when the slider is inserted into the sleeve member is set smaller than a distance between the connection hole and a back of the blade, and thereby the back of the blade is biased against the inner surface of the sleeve member, so that a space is kept between an edge of the blade and an opposite another inner surface of the sleeve member while the blade is sliding, and the first engagement protrusion and the second engagement protrusion are located in straight and parallel with the sliding direction of the slider, thereby when inserting direction of the slider into the sleeve member is reversed, biased direction of the blade is also reversed.
 2. The cutter knife in claim 1, wherein the slider is provided with a grip surface, at center in the sliding direction, on which user's finger is to be pressed, and the first engagement protrusion and the second engagement protrusion are located on a first extending portion and a second extending portion, which extend towards in opposite directions to each other from the grip surface.
 3. The cutter knife in claim 2, wherein the first extending portion and the second extending portion are of frame-like configuration, by which an elasticity for biasing is realized. 